Lecture 6

Question 1

The reduction in terrestrial primary production with increasing latitude is also related to seasonal variations in the input of _______, _________, and _______

Answer 1

solar energy, day length and temperatures

Question 2

Biome

Answer 2

A biome or biogeographic region is a major ecological community that stretches over thousands of square kilometres and is related to the general climate and topography that determines biota habitats.

Question 3

The interaction of ______, _______, and _______ generates the processes that constitute the terrestrial ecosystems of Subarctic and Arctic regions.

Answer 3

flora, fauna and the associated physical environment

Question 4

4 main variations in physical properties of soils

Answer 4

climate, topography, drainage and parent materials (i.e., bedrock or sediments)

Question 5

Describe vegetation in the low arctic for these specific:

Riparian Zones

Rolling Uplands

Lowlands

Elevated Habitats

Answer 5

In the Low Arctic, riparian zones along rivers and streams are occupied by herbaceous and tall shrub vegetation.

Rolling uplands north of the tree line generally contain low shrubs of Salix and Betula along with dwarf shrubs of the various heath species that fit within a matrix of upland sedges, including cottongrass tussocks and forbs. Beyond these landscapes are large areas dominated by sedges, dwarf shrub species (mainly heaths), and scattered low shrubs of Salix and Betula.

Lowlands that are imperfectly drained and the more expansive coastal plain lowlands are dominated by wetland sedges, grasses, and mosses forming extensive mires.

Elevated habitats generally contain low or dwarf shrubs, cushion plants, lichens and graminoids; species adapted to well drained or intermediately drained soil.

These are the major vegetation types within the Low Arctic of Alaska, mainland Canada and much of mainland Siberia.

Question 6

Boreal Forest: Taiga

Answer 6

Boreal forests are composed largely of coniferous, evergreen vegetation dominated by spruce (Picea), pine (Pinus), fir (Abies) and tamarack/larch (Larix) that occupy a broad circumpolar belt across the Northern hemisphere covering an estimated area of 15.8 million km2 globally (Figure 6-2).
Regions occupied by boreal forest are dominated by cold, dry air masses (continental Arctic, continental Polar) for most of the year. Mean winter temperatures commonly vary from –20oC to –30oC. Temperatures rise rapidly in the spring and summer in response to increasing day length and insolation.

Mean summer temperatures range from 12oC to 15oC. The large annual temperature range is characteristic of boreal forests. The growing season is short. The frost-free season varies from 50 to 100 days and temperatures remain above 10oC for at least 30 days in the northernmost regions and 120 days in the southernmost regions. Precipitation is largely cyclonic in nature and strongly associated with atmospheric processes operating along the polar front (see Figure 2.8 in Module 2). So pronounced is the influence of the polar front that many researchers consider the southern boundary of the boreal forest to coincide with its mean January position. Mean annual precipitation is generally less than 600 mm. Most precipitation falls in summer, but more than 100 mm of snow can fall over the long winter season.

Question 7

name two dry air masses found affecting the Taiga in boreal forest

Answer 7

continental artic and continental polar

Question 8

Soils associated with boreal forest are typical of mid-latitude and Subarctic regions. In areas where permafrost is ________/_______

Answer 8

absent/sporadic

Question 9

Podzols

Answer 9

Podzols are coarse-grained mineral soils developed on parent materials derived from glacial tills and glaciofluvial sediments and are the dominant soil order present in the Subarctic region.
-Plant litter that accumulates on the surface of these soils decomposes slowly resulting in a thick layer of organic matter. Podzols exhibit strong acidity (pH 3.5-4.5) deriving from the intensive leaching of cations associated with humid climates.

Question 10

Podzols, Luvisols and Brunisols develop on well to imperfectly drained upland surfaces where…

Answer 10

permafrost is absent/sporadic

Question 11

The _________ of organic matter, and iron and aluminum oxides (e.g., limonite (Fe2O3.H2O) and gibbsite (Al2O3.3H2O)), and their accumulation at depth characterize these soils (Figure 6-3). The low nutrient status of Podzols makes these soils relatively ________

Answer 11

translocation

infertile

Question 12

Where parent materials are more alkaline in character due to the presence of ________ minerals, Luvisols and Brunisols develop.

Answer 12

carbonate

Question 13

Luvisols

Answer 13

Luvisols are fine-grained mineral soils derived from glacial tills, and glaciolacustrine and glaciomarine sediments.

The translocation of clay minerals and their
accumulation at depth characterizes Luvisolic soils. In comparison with Podzolic soils, the high nutrient status of Luvisols makes these soils relatively fertile.

Question 14

Luvisols vs. Podzolic soils

Answer 14

In comparison with Podzolic soils, the high nutrient status of Luvisols makes these soils relatively fertile.

Question 15

Gleysols

Answer 15

Gleysols are mineral soils associated with environments that experience persistently high water tables, especially where the ground surface is underlain by permafrost. Weakly differentiated soil horizons are indicative of prolonged water saturation and strongly reducing conditions that impart dark soil colours

Question 16

Histosols

Answer 16

Histosols are composed largely of decomposing plant litter (peat) that is subjected to prolonged water saturation. These environments are characterized by the slow anaerobic decomposition of plant litter that allows a considerable thickness of organic matter to accumulate within lowland depressions.

Question 17

______ and ______(organic soils) develop in poorly drained lowlands, on river floodplains and along lake margins.

Answer 17

Gleysols and Histosols

Question 18

The North American boreal forest is commonly subdivided into three forest regions:

Answer 18

the open lichen woodland:
Open lichen woodlands consist of an open canopy forest with trees irregularly spaced as much as 25 metres apart while light-coloured lichens and mosses dominate the understory. White spruce (Picea glauca), black spruce (Picea mariana), dwarf birch (Betula glandulosa) and Labrador tea (Ledum spp.) dominate the typical spruce-lichen woodland on better drained sites associated with Podzolic and Brunisolic soils (Figure 6-3). Lichens (primarily Cladina spp.) and mosses (Sphagnum spp.) characterize the understory vegetation. In poorly drained Gleysolic soils the vegetation cover is characterized by the presence of widely scattered black spruce (Picea mariana) and tamarack (Larix laricina) associated with a variety of shrubs including Labrador tea (Ledum spp.), birches (Betula spp.), willows (Salix spp.) and heaths (Vaccinium spp.) (Figure 6-3). Mosses (e.g., Sphagnum spp., Aulacomnium spp.) dominate the ground cover. Coniferous tree species appear to be well adapted to cold, moist soils because they are able to tolerate nearly saturated soils with strongly acidic, low nutrient supply conditions.

the northern coniferous forest:
The composition of the northern coniferous forest varies regionally across the circumpolar North (see Figure 37, p. 112 in the 1998 AMAP report listed in the Supplementary Resources). In northern Canada these forests are characterized by a closed canopy consisting largely of white spruce, black spruce and balsam fir (Abies balsamea) with some trembling aspen (Populus tremuloides), balsam poplar (Populus balsamifera), jack pine (Pinus banksiana) and paper birch (Betula papyrifera). Soils consist primarily of well-drained Podzols in regions underlain by the Canadian Shield, and Luvisols and Brunisols in regions underlain by calcareous glacial, glaciolacustrine and glaciomarine sediments. Common understory species include shrubs such as alder (Alnus spp.), Labrador tea, bearberry (Arctostaphylos uva-ursi), blueberry (Vaccinium angustifolium), herbs, club-mosses and feather-mosses, and lichens.
Learning

the mixed forest:
The mixed forest occurs south of the Canadian Shield where soils are deeper and the climate is less severe. Podzols remain the dominant soil order in this region, but greater areas of Luvisolic and Brunisolic soils are also present. The milder climate and more nutrient-rich soils allow for broadleaf, deciduous species to outperform or co-exist with coniferous, evergreen species. White spruce, trembling aspen, paper birch and balsam poplar dominate these forests.

Question 19

Name 4 broadleaf deciduous tree species

Answer 19

such as paper birch, trembling aspen, balsam poplar and willow (Salix spp.). The nutrient-rich groundwater and moist, warm, well-aerated soil conditions that develop during the summer growing season favour deciduous over evergreen species.

Question 20

5 horizon types

Answer 20

Ah

Ae

Bf

Bc

C

Question 21

Podzolic soil profile.

Answer 21

Podzolic soil profile: the diagnostic soil horizons are the pale grey eluviated Ae horizon and the underlying Bf horizon that is enriched in iron and aluminum oxides. The bright orange and yellow colours of the Bf horizon are indicative of the oxidation of iron and aluminum oxides in a well-drained soil. The soil is developed on a sand and gravel parent material exposed at the base of the pit.

Question 22

Brunisolic soil profile

Answer 22

Brunisolic soil profile: the diagnostic soil horizons are the weakly developed eluviated Ae horizon and the underlying darker coloured Bm horizon that is slightly enriched in iron and aluminum oxides, indicated by the brown colours. The soil is developed on a sandy parent material exposed at the base of the pit

Question 23

Grey Luvisolic soil profile. Luvisolic soil profile

Answer 23

the diagnostic soil horizons are the thick, darkcoloured Ah horizon developed beneath the vegetation cover and the underlying grey brown Bt horizon that is enriched in clay. These soils develop on clay-rich parent materials.

Question 24

Gleysolic soil profile. Gleysolic soil profile:

Answer 24

the diagnostic characteristics of these soils are the weak development of distinct horizons and the dark grey and black colours indicative of the reduction of iron and aluminum oxides under anaerobic conditions in poorly-drained soils (i.e. gleyed Bg and Cg horizons).

Question 25

In North America, the arctic tree line is
approximately equivalent to the position of the __ degrees Celsius mean July isotherm and coincides approximately with the mean July position of the polar front and the southern limit of continuous permafrost.

Answer 25

10oC

Question 26

cryoturbation

Answer 26

cryoturbation (frost churning) refers to the mixing of materials from various horizons of the soil down to the bedrock due to freezing and thawing.

Question 27

Periglacial landforms known as ______ and _______ develop in poorly drained landscapes within the forest-tundra biome in association with discontinuous permafrost.

Answer 27

palsas and peat plateaux

These features develop within wetlands where peat moss begins to accumulate on a waterlogged sedge meadow. Over time peat accumulates to a sufficient depth that portions of the peat fail to thaw in summer. Freezing of groundwater within peat contributes to the formation of segregated ice lenses. The growth of these ice lenses is sustained by the continuous movement of groundwater towards the freezing plane within the peat until the moisture supply is depleted. The growth of segregated ice lenses displaces the peat surface upwards, a process referred to as frost heaving, causing a raised mound of peat to appear. As peat mounds emerge from the wetlands a positive feedback mechanism is initiated that operates to insure further growth of the palsa. The newly formed palsa is swept free of winter snow allowing frost to penetrate deeply into the underlying peat. Frozen peat conducts heat in winter more easily than wet peat in summer so more heat is lost from the palsa in winter than is gained in summer. As a result the core of the palsa continues cooling facilitating further growth of segregated ice lenses and frost heaving of the ground surface.

Question 28

Palsas

Answer 28

Palsas are peaty mounds that possess a core of alternating layers of segregated ice and peat or mineral soil

Question 29

Peat plateaux

Answer 29

are broad, flat-topped expanses of frozen peat containing segregated ice

Question 30

“drunken forests”

Answer 30

Trees growing at the margins of these peat landforms tilt outwards as the ground heaves beneath creating

Question 31

At high latitudes growth of woody vegetation is restricted by a lack of ______ and ________

Answer 31

summer warmth and available plant nutrients, especially nitrate-nitrogen

Question 32

The treeless circumpolar tundra spans an estimated area of __ million km2 globally

Answer 32

25

Question 33

Riparian zones along rivers and streams in the Low Arctic are occupied by ______ and _______ vegetation

Answer 33

herbaceous and tall shrub vegetation.

Question 34

In the High Arctic of the Canadian Archipelago the vegetation is…

Answer 34

the northern portion of the Taimyr Peninsula and the Russian Archipelagos the vegetation is shorter and sparser. There are few wetland areas, but much of the landscape is covered with cushion plants, lichens and mosses or with scattered vascular plants in a substrate of mosses and lichens. These are the polar steppes. Other vast areas known as polar deserts have almost no plant cover. Cushion plants such as purple saxifrage (Saxifraga oppositifolia), draba (Draba spp.) and Arctic poppy (Papaver radicatum) occur with small amounts of mosses and lichens.

Question 35

Regions occupied by tundra are dominated by cold, dry air masses: name the two air massses

Answer 35

(continental Arctic, continental Polar) for most of the year.

Question 36

felsenmeer

Answer 36

Happens in tundra regions

On upland surfaces frost action produces accumulations of angular rock clasts known as a block field or

Question 37

cryosols

Answer 37

Decomposition of organic materials and primary minerals occurs slowly in high latitude environments and over most of the tundra region the typical soil profile consists of an organic surface layer of variable thickness overlying a strongly gleyed mineral soil.

Question 38

2 types of cryosol, describe eacch

Answer 38

Turbic Cryosol:
if permafrost lies within two metres of the ground surface and the effects of cryoturbation are evident (e.g., presence of patterned ground, )

Static Cryosol:
if permafrost lies within one metre of the ground surface with no evident cryoturbation

Question 39

Shrub Tundra

Answer 39

Woody shrubs such as dwarf willow, dwarf birch, alder and Labrador tea dominate shrub tundra vegetation communities (Figure 6-8). On well-drained slopes characterized by Brunisolic Turbic Cryosols and Static Cryosols these shrubs are associated with heath plants, grasses, mosses and lichens. Common heath plants include Arctic white heather (Cassiope tetragona), crowberry (Empetrum nigrum), bearberry (Arctostaphylos uvaursi), rock cranberry (Vaccinium vitis-idaea) and bilberry (Vaccinium uliginosum). The understory vegetation cover is dominated by grasses such as alpine meadow grass (Poa spp.) and polar grass (Arctagrostis latifolia), mosses and brightly coloured lichens.

Question 40

Wet Tundra (Sedge Meadows and Tussock Tundra)

Answer 40

Wet tundra vegetation communities are dominated by sedges (Carex spp., Eriophorum spp.), Arctic willow (Salix arctica), polar grass (Arctagrostis latifolia), alpine bistort (Polygonum viviparum) and mosses and occur on poorly drained mineral soils characterized by Turbic Gleysolic Cryosols (Figure 6-9). Poorly drained organic terrain within the continuous permafrost zone is characterized by the presence of ice-wedge polygons. Soils in these areas are Turbic Organic Cryosols. Mosses dominate the elevated, better-drained peat areas along with dwarf birch, Labrador tea, heath and bog rosemary (Andromeda polifolia). The surrounding wetland is completely dominated by sedges and mosses.

Question 41

Mesic Tundra

Answer 41

Mesic tundra vegetation communities develop in proximity to late lying snow banks (Figure 6-10). Soils in these microhabitats are well drained Static Cryosols. Grasses such as bluegrass (Poa spp.) and fescue (Festuca spp.), Arctic white heather (Cassiope tetragona) and Arctic willow (Salix arctica) dominate the ground cover. Other common plants include saxifrages (Saxifraga spp.), Arctic poppy (Papaver radicatum), Arctic avens (Dryas integrifoila), mountain sorrel (Oxyria digyna), cinquefoil (Potentilla spp.) and buttercups (Ranunculus spp.) along with a variety of mosses and lichens. Brightly coloured lichens such as Rhizocarpon geographicum and Alectoria spp. are common on exposed rock surfaces.

Question 42

Polar Steppe Communities

Answer 42

Polar steppe plant communities develop on well to imperfectly drained, fine-grained soils (Static Cryosols) in the High Arctic often in association with the tops of high-centred ice wedge polygons (Figure 6-11). Ground cover is dominated by woodrushes (Luzula spp.), foxtail grass (Alopercus sp.), goose grass (Puccinellia spp.), snow grass (Phippsia sp.), cushion plants such as chickweed (Cerastium spp.), draba (Draba spp.), saxifrage (Saxifraga spp.), moss campion (Silene acaulis), sedges (Carex spp.) and a variety of mosses and lichens.

Question 43

Polar desert

Answer 43

The term polar desert is applied to barren areas (i.e., plants cover less than 5 percent of the surface area) associated with rock outcrops, felsenmeer and sterile gravel (Figure 6-12). A variety of lichens (e.g., Rhizocarpon geographicum, Umbilicaria spp., Cladonia rangifera) dominate polar desert plant communities. Cushion plants such as saxifrages (Saxifraga spp.), chickweed (Cerastium spp.), Arctic avens (Dryas integrifolia) and Arctic poppies (Papaver radicatum) are common members of polar desert communities.

Question 44

An area, in high latitude, with plant cover of less than 5 percent of the surface area is called a

Answer 44

polar desert

Question 45

Fjell Fields

Answer 45

Upland surfaces mantled by felsenmeer present extremely dry habitats characterized by a thin, discontinuous vegetation cover (i.e., less than 20 percent of the ground surface) consisting of Arctic avens (Dryas integrifolia), heaths (Cassiope sp., Empetrum sp.) including alpine azalea (Loisleuria procumbens), Arctic poppy (Papaver radicatum) and lichens (Figure 6-13).

Question 46

The Stordalen wetland is an example of..

Answer 46

The Stordalen wetland with its hummocks and depressions is one example of how small changes in the microclimate can provide herbivores such as lemmings or reindeer with access to different plant species at different times as a result of changes in snow cover or timing of growth.

Question 47

DO YOU KNOW WHAT THESE MEAN?

Air Mass: 
Anaerobic Respiration: 
Atmosphere:  
Broadleaf Vegetation:  
Bryophyte: 
Coniferous (or needleleaf) Vegetation: 
Cushion Plants: 
Deciduous Vegetation: 
Felsenmeer:  
Forb: 
Fruticose Lichens:  
Herb:  
Hydrosphere: 
Lithosphere:  
Mesophytic (Mesohygrophytic): 
Palsa: 
Peat Plateau: 
Polar Front: 
Riparian Environment:  
Translocation:

Answer 47

Air Mass: a large body of air having characteristics of temperature, moisture, and pressure that are approximately uniform horizontally. E.g., the continental Arctic air mass is characterized by a mean annual temperature if -400C and a mean annual humidity of 0.1 g/kg, and the continental Polar air mass is characterized by a mean annual temperature if -100C and a mean annual humidity of 1.4 g/kg.

Anaerobic Respiration: The process of generating energy by the oxidation of nutrients using an external electron acceptor other than oxygen.

Atmosphere: The gaseous envelope surrounding Earth.

Broadleaf Vegetation: Plants having relatively broad rather than needlelike or scalelike leaves

Bryophyte: A plant of the Bryophyta, a division of photosynthetic, chiefly terrestrial, nonvascular plants, including the mosses, liverworts and hornworts.
Coniferous (or needleleaf) Vegetation: Any of the various mostly needle-leaved or scale-leaved, chiefly evergreen, cone-bearing trees or shrubs (e.g., pines, spruces, firs and tamaracks).

Cushion Plants: A type of low-growing plant having many closely spaced short upright shoots, typical of alpine and arctic habitats.

Deciduous Vegetation: Plants that shed their foliage (leaves or needles) at the end of the growing season.

Evergreen Vegetation: Plants that retain their leaves or needles in all seasons.

Felsenmeer: The term felsenmeer comes from the German meaning ‘sea of rock’. In a felsenmeer (also known as a block field), frost action has broken up the top layer of the rock covering the underlying rock formation with jagged, angular boulders.

Forb: Any herbaceous plant that is not a grass.

Fruticose Lichens: A term relating to the branching nature of some lichens.

Herb: Plants or plant parts that are fleshy as opposed to woody; a herbaceous plant.

Hydrosphere: A term that relates to the water present at the Earth’s surface, including rivers, lakes, groundwater and water vapour in the atmosphere.

Lithosphere: The lithosphere includes the crust and the uppermost mantle, which constitute the hard and rigid outer layer of the Earth.

Mesophytic (Mesohygrophytic): A land plant growing in an environment having an average supply of water.

Palsa: (plural: palsas or palsen) A term from the Finnish language meaning “a hummock rising out of a bog with a core of ice.” Bugor and bulginniakhs are general terms in the Russian language (the latter of Yakutian origin) for palsas and pingos. Palsas are low, often oval, mounds of frost heaved peat or soil which contains permanently frozen ice lenses. They often occur in groups and are characteristically found in areas with discontinuous permafrost.

Peat Plateau: Peat plateaux are structures of coalesced palsas that form a continuous elevated flatland area usually in a peat bog.

Polar Front: The region or boundary separating air masses of polar origin from those of tropical or subtropical origin. The position of the polar front during winter in a particular hemisphere is at approximately 30° latitude, while in the summer it is at approximately 60° latitude. The convergence of warm and cool air masses along the polar front often produces cyclonic wind systems.

Riparian Environment: Plant habitats and communities along river margins and banks characterized by plants that tolerate water saturated soils.

Translocation: A term that refers to the downward movement of solid (e.g., clay minerals, oxides) and dissolved materials (e.g., plant nutrients such as potassium (K+), phosphorus (PO43-), nitrogen (NO2-, NO3-)) within soils.